The invention relates to a wet-running submersible motor according to the preamble part of patent claim 1.
In DE-38 28 512 A1 there is shown a submersible pump unit with a wet-running motor, in which the motor, in a housing which is submersed into the fluid to be delivered, comprises a rotor which is surrounded by a split tube and is carried by a central shaft which is supported at both end regions of the motor in sliding bearings. To the pump side the shaft protruding out of the motor housing is surrounded by a sealing formation in order to seal the rotor space of the motor towards the pump side. Furthermore the shaft is formed hollow over its whole length and is connectable, at the end protruding out of the motor on the pump side, to a centrifugal pump. The shaft is at least partly filled with a fluid and at its end on the pump side is closed in a fluid tight manner with a closure stopper so that the fluid may not exit the shaft. Finally the space formed by the split tube, for the rotor of the motor is filled with fluid or the purpose of cooling. Via the intermediately connected cooling fluid in the hollow shaft, the motor heat is transmitted to the pump region or to the delivery fluid located here, in order to thus cool the motor.
During the transportation of the previously described wet-running motor or of the submersible motor pump unit, from the manufacturer to the location of application, where appropriate with intermediate storage of the motor or the unit until its point of time of application, considerable damage may occur on the wet-running motor due to fluid loss from the rotor space. As a result of this fluid loss, for example due to freezing temperatures during the transport and/or storage of the motor and the entailed destruction of the sealing formation, an insufficient cooling of the motor on later operation occurs, so that an overheating of the motor with again damage resulting therefrom is the result. The rotor space no longer contains adequate cooling fluid, since part of this has been previously lost. A further disadvantage lies in the fact that the packaging of the wet-running motor becomes damaged by the fluid running out of its rotor space and the demands made of it are no longer fulfilled. One has also therefore proceeded to deliver the wet-running motor with an unfilled rotor space or only partly filled with fluid. The motor must then however be completely filled with fluid before its installation or its starting up. This is time consuming and is not always carried out properly according to the instructions, this means that a complete filling of the rotor space is not ensured so that again an insufficient cooling of the motor is the result. Furthermore it must be ensured that the power data of the delivered motor are guaranteed at the customer. For this the wet-running motor before its delivery is checked with regard to this data with a filled rotor space at the manufacturer, is again subsequently emptied and then delivered in order to avoid the mentioned damage. In particular the emptying of the rotor space is time consuming and complicated, and with motors of a low power, for example up to about 4 kW, which may be manufactured relatively cheaply as a mass product, is a considerable cost factor.